Means for generating and cutting irregular gears.



E. R. FELLOWS.

MEANS FOR GENERATING AND CUTTING IRREGULAR GEARS.

' APPLICATION FILED APR. 22, 1915.

mgwm. A hmm July n, 1916.

5 SHEETS-SHEET I E. R. FELLOWS.

MEANS FOR GENERATING AND CUTTING IRREGULAR GEARSx APPLICATION FILED APR..22.1915.

l 9 1L W3 39 L n Patented July 16 E 5 SHE ETSSH ET E. R. FELLOWS.

MEANS FOR GENERATING AND CUTTING IRREGULAR GEARS.

APPLICATION FILED APR. 22,19I5.

9 :i @Q. 55% 1 Patented July 11, I916.

' HEET a.

5 SHEETSS E. R FELLOWS.

MEANS FOR GENERATING AND CUTTING lRREGULAR GEARS.

APPLICATION FILED APR.Z2,1915- 3. 9 A 9&39 1 Patented. July 11, 1916.

.5 SHEETS-SHEET 4.

,LEQIUJEWL E. R. FELLOWS. MEANS FOR GENERATINGAND CUTTING IRREGULAR GEARS; APPLICATION FILED APR. 22, I915.

Patented July 11,1916.

\ 5 SHEETS-SHEET 5.

To all wile m may cancer 2.:

Be it known. that if, lawii: a citizen of the limited Stains,

' l in the con .ty

/eri'nont, hx'ziv'e inv' tairi new atmi useful improvements in. for Generating and Cu or which the foilcm'ing -'ilie present invention relates to the art of generating and cutting teeth on irregular gears, by which i mean gears having teeth arranged on a pitch line which is otherwise than concentric with the axis about which either the is designed to rotate or a pinion meshing with the r is designed to revolve.

In my application for patent, Serial Numher 858,132 iilecl .iugust 191 i, 1 have illustrated a means for generating and out ting the teeth of such a wherein the gear is held by floating holder and is given increment, relatively to a tootirgcneiwils ing cutter (hiring the g anti cutting, operation, which is similar to the relativc movement between the gear and the pinion with which it designed to mesh.

The apparatus anal means which form the subject of the present invention of the same general nature as those shown in my application aforesaid, out possess modifications and refinements having for their ohicct to accomplish the desired end with less mechanicalresistance ancl with possibly greater accuracy.

Briefly stated the principal object of the present invention is to provide as means for so moving an irregular gear hlanl; trans latively and rcvolubly, in connection with generating motion oi a gear-shaped planing; cutter, or other cutter capali ic of cutting gear teeth of the riesirccl form, during, the

cutting operation to produce exactly the same relative moveme tween the .lolaiilr and the cutter in directions transverse to tin axis of the blank, as take place between the gear anti the standard pinion with. which it is designed to run in mesh, and to ellect this movement in a positive manner anti with the minimum of frictional or other resistancc.

The particular gears of which the teeth.

are to be generated anti cut .oy who p ey apparatus include an rterrial tary molioii when either the external. gear or the internal gear is rotated. relatively to the other.

Une iorm oi? the ihcai'is which I have adopted and desire to protect in the present application for giving the desired movements to the gear blank consists of a set of master gears and pinions, to one which master the blank connected, and of which one of too pinions is used as the rlrivcr for giving the generating movement to the gear being cut, in connection with a cutter which may he oi? any sort capable of goneratiiigthe forms of gear teeth at the same time that it cuts them, by a combination of relative increments between the cutter and. the work piece. One form of such a cutter, here illustrated, has peripheral projections shaped similarly to the teeth of a spur gear and arranged on a pitch line aproxhngrlcly equal in diameter tothc pitch. line o1": such driving pinion. (ltheriorms of means for the same purpose herein illus tralccl comprise co-acting elements connected with the "master gear and the table on which the work aolcler is supported for positively sh ting the work holder when receding portions of the pitch line of the master approach the driving pinion. Essentially the same means, with minor variatioiis aolapterl to the particular w rlr in haiui, may he prmiclecl and arranged for cutting any shape or character of internal or external irregular gear, Wherefore the particular description which follows of the or "lmtl'iillfll'li of such means adapted to a pan cu. tins: an internal ear. Pie. 2 is a similar view showing the apparatus arranges; for cutting on .i Fig. 31s a sectional plan. "view oi: the worlr lioliier talten view of the parts below the line'66 of Fig. 5. Fig. 7 is a sectional View showing the principles of the last two figures applied for cutting an internal gear. Fig.

8 is a plan view of parts below the line 8- 8 of Fig. 7.

The same reference characters indicate the same parts in all the figures. J

Referring to Figs. 1 to'3of the drawings, 10 represents a fixed table mounted on the base of a gear cutting machine and having a flat and smooth upper work-supporting surface. It 13 mounted on a qulll 11 secured I in the Work suporting part of a gear cutting machine, such. as, for example, the carrier I shown in my prior Patent No. 676,227. A

spindle 12 is mounted rotatably in the quill and contains an arbor 13. Said spindle may he considered as the driving spindle for imparting generating movements to the Work. 14: represents a cutter WlilCll is made so as to generate and cut gear teeth by a combi-- nation of axial cutting movements with rotatory generating movements. This cutter has projections 15 similar in outline, and equal in pitch to the teeth of a standard pinion or gear and arranged on a circular pitch line, but (littering from the teeth of the ordinary gear in that theedges of the teeth at the end face of the cutter are made as cutting edges and the faces'at the sides and extremities of the teeth and at the bottom of the spaces between the teeth are backed 05 .or inclined toward the axis of the cutter to give clearance in the cutting operation. This cutter is mounted on a spindle 16 by which is given the necessary reciproeating cutting movements and rotatory gcncrating movements. Without limiting the present invention to any particular organized machine, I may say that I have applied the same to a machine of the type illustrated 1 in my Patents No. 579,708 of March 30, 1897; No. 676,227 of June 11, 1901; and No.

1,028,343 f June 4, 1912, and that in practice I have rotated the spindle 12 and have rotated and reciprocated the spindle 16 by mechanisms essentially the mechanisms employed for rotating the Work holding spindle and for reciprocating and patent; i..

The earblank onlwhich the teeth are being cut in'the' arrangement shown in Fig. '1 is designated 17 and it is mounted upon a floating Work holder 18 which rests upon the rotating the cutter spindle shown in the said table ll) and is free to move inany manner- In any direction over the surface ofsuch table, except that it is restrained-from i'otat- .ing completely about the axis of splndle 12 the muster gear and that part of same as the combined former and master ear 23, hav- I i 1 D mg an mternal hue of teeth 24 arranged on 'a pitch line of the same o'utlinc as the pitch line of the teeth to be cut in the gear blank The part which constitutes the former is an internal rib 25 of which the outline cor esponds with the pitch line of the teeth 24. In the illustrated embodiment of Figs.

1 and 3 the surface of the rib Q5 conforms exactly in outline, curvature, and irregulan ity to the pitch line of the teeth il lund is in efi'ect a continuation of the pitch surface of such teeth, but this condition may be altered, as I 'Wlll presently show. Reference to 3 will show the shape of the fo'gmcr .25 and'master gear From this View it will be clearly am'mrent that the line of the teeth is irregular in the sense of not being}; on a circleconcentric with the geometric axis 26" of the master gear, although the line of the teeth forms a Syl-TllIlGUlQfll"Q00" metric figure. This gear has four, equal and symmetrical lobes. the approximate centers of curvature of which are not in the geometric a of the gear.

Fixed upon the arbor 13 is a c m1hiuod driving having teeth 27 meshing With the teeth of. it which constitutes the former having a peripheral surface 28 conforming to the pitch surface of the iecthaud being inellect the prolongm tion of such pitch surface. This pinion is the driving pinion of the work holder; it is keyed to the arbor 13 and is clamped there-- on by a nut 29. The pitch diameter ofthe pinion 26 is approximately equal to the pitch diameter of th e'teeth 15 of cutter l4,

and the axis of" the pinion is approximately In line with the axis of the cutter, that relatively to the cutter, to the proper depth 7 for forming the teeth, and that the present drawln s illustrate the condition thecutter has been caused to cut to the requireddepth intd the tooth bearing portion of'the work that the condition illustrated and ubovedescrihed obtains; In this conditioul the point in the pitch line oi. the cutter which comes tiingent to the pitch lUlO of the gear-blank is in exact alincment with the pinion and formel flhithc pinionlflll after the" depth feed has been completed. It is after crooner point of tongency between the pitch lines of tlie master gear and the master pinion,

The combined pinion and former 26 is oneoili it number of similar combined plnlons.

end formers 30, 31, 32, 33-snd 34:, which are arranged st intervuls about the periphery of muster gear and are identical as to diameter and pitch with the driving pinion. the surrounded by the said pinions ispleced an. irregular external] gear 35 havh 36, with which'is associated a com or 3?, The surface of the former 3'? hes the some outline as the pitch line er the teeth 3% end conforms exactly with this pitch line, ouch egeiul element of the former surface being in line with at corresponding point ct the pitch line of the teeth. In other words, the pitch line of the teeth and the surface of the former are in effect partsv of the some geometrical surface, and the relotion between the former surface and pitch line oi this gear is the same as that already described between the former surface and pit en line of the master internal gear and of the driving pinion 25, end that of the other pinions. The pinions 26, 80, 31, 32, 33 end 34 are so arranged about the common unis 26 0i the irregular gears 23 and 35 that the centers of the pinions on opposite sides oi the gear 35 are in lines passing; through the point 26, which is the common axis of revolution of the entire collection of gears and pinions; and the outline of the combined external gear and former 36 is so designed relatively to the pitch outline of the it rnol gear and former 23 that in all positions of revolution of the external gear about this axis, the same condition wi l hold and each of the pinions will be in mesh with both the internal and external gears, and their former surfaces will remain in tangent contact with the peripheral surface of the external former 3"! and the surface of the internal r'ormer 25. I

All of the elements described. except the pinion 26, are flouting, that is free to shift noon the table 20 and are confined only by the in'liermcshing oi their teeth and the tengent contact of their formers with one onother, and by the restraint from complete rotation of the entire collection imposed by the stop or abutment 10. Thus when the driving pinion is rotated the-master goers -23 end are rotated in opposite directions about the common axis 26, and such axis is shifted in the manner necessary to maintain the pitch surface of the master internal gear tengent to the pitch surface of the driving pinion. The reaction of the gear 35 on the driving" pinion and the inter-reactions between thccxtcrnul and internal master gears and the intermediate pinions combine so to shift the worlc holdcr as to maintain be tween the blank 17 and the cutter 14 exactly the same condition of rolling tangent from the teeth of the master pinion,

The shape and pitch of the teeth out in r the work may be made identical in form, dimensions, and pitch with the teeth of the master gear by using a cutter At of which the tooth-like projections designed sccording to well. understood principles to generate such teeth, but the invention is not limited to u means for securing such erect identity of the work to the gear, for it is part of my contemplation to gencrete teeth of other forms and. pitch. in the Worlt Tl'lese chsracteristics of the teeth out in the Work ere governed entirely by the corresponding characteristics of the cutter. What I have accomplished. by the present invention is to produce exact correspondence between the pitch line of the teeth out in the work and the pitch l ne of the teeth in the master gear.

An external gear having at pitch line or surface conforming exactly to the pitch surface of the combined gear and former 35 is produced by the some means in substantially the some way, as shown in Fig. 2. it gear blank is mounted upon the holder 18 and is ulincd with the combined external gel and former 35 by means of a. stud 39 passing! from the axis of the gear 35 and clunmed thereto by a nut 39, and upon which the blunlc 38 is clamped by a, nut 38. This stud is free to rotate within its bearing in the holder 18. The holder and the gear blunk are then given trunslativcmovements with relation to the cutter which correspond to the irregularities of the external muster gear 35 insteudfo'i to those of the internal gear. The same pinion 26 serves in this case also the driver. the entire collection oi gears and pinions being: then placed at the opposite sidcot the axis of the spindle so that the acting portion of the cutter will be at the forward side of the cutter spindle, us before.

In the foregoing description I have described the formers us bcinp; identical with the pitch lines of the gears whcrcwitb they are respectively associated; but l do not limit the invention to an apparatus in which this relation occurs, since the some results 'muy be secured it the formers are similar in it is associated in such :1 n'mnncr that the 1 normal distance bctwccn corresrmndhig points in the former outline and the pitch was line is uniform throughout the entire cir-- distance by which the formers of the master gears are so Withdrawn is equal to that by which the former elements of the pinions are projected, whereby the distances between the centers or axes of the intermeshing gears orpinons remain the same though the formers were in exact almcment or identity Withthe respective pitch lines. in either case, Whether the former is identical with the pitch line of the gear or is similar to it, there is a correspondence in outline between the former and the gear, wherefore the term correspond, or corresponding, used in the following claims, is intended to embrace both the condition of identity shown in F1g,

'3 and that of similarityshownin Fig. 4, between the formers and the gear pitch lines.

The present invention is not limited to a Work holding device in which the master gear is retained in mesh with the driving pinion by such a collection of iicmtinn gears and pinions as has been hercinhet de-' scribed. The san'ie results, in so far as'con cerns positively retaining the mast 1' gear n mesh w t" the di, mgr pinion are .ecurcd by the means illustrated in Figs. 5 and 6,

designed for cutting external gears, and in.

F igs. 7 and 8 arranged for cutting internal gears. And first as to Figs. 5 and 6; the same reference charactersare used in these figures to designate'parts corresponding to those Which are shown in Fig. 2. In'the construction now being described I provide a calm or former 419 which is secured to the master gear 35 ymcans of screws 1-1. The periphery of the former bears against the-periphery of a roll 42 which is mounted to turn about a stud 43 which is fixed in the table 10 and is made steady at its upper end bye. been (a plate is. lined to an "up-- standing lip to on the table. The gear has a formessurfacc or portion 3", coinciding with the pitch line of the gear, like the former shownin 2, which bears against the formerportion 28 of the driving pinion .26. The outline of the former is similartothat of the'former 37, and it is secured with its major axis at right angles to the major jaxisof'the former 37, as appears -from Fig. 6. The relation between these two formers 1S therefore such that the distanco from any point, c, in the plied for cutting surface of the former 40 to the projection in the plane of said former of the point I; in the former 37 (that is, the pitch line of the master gear) diametrically opposite through the axis of the master gear, is equal to the distance from any other point 0 in the surface of former 40 to the projection in the same plane of the diametrically opposite point (I in the surface of the former 37 and pitch line of the. master gear. Consequently,

as the driving pinion and the abutment roll 40 are at an invariable distance apart, the effect of these two formers is to cause such shifting of the work holder bodily as will maintain the former surfaces 37 and 28 in tangent contact; the former 4O acting to bring points in the receding parts of the former 37 up to the former 28. The master gear 35 and the former -fl-ll arc lmyctl by means of a key ill to a tubular hub portion 51-7 on the work holder 18", on which the stud 39 carrying the worlr piece (gear blank) 38 is held against rotation by a key 18. The former 40 has a second surface 49 which is concentric with the axis of the stud 30, that is, the common axis of the former 40 and the master gear, and the table carries-fixed ahutmcnts 50 on opposite sides of the surface 4.5) and in tangent contact therewith to' guide the work holder and prevent its shifting to either side of the line between the centers of the driving pinion. and ,"of the abutment roll 42.

in Figs] 7 and 8 the same principle is upan, internal gear. with this modification that the roll l2. which corresponds to'the roll 4-), bears against an teFnal cam surface 51 on the master internal gear 23, such surface being, similar at all points to the pitch line of the teeth of said inaster gear and to the former surface 25 thereof.

It will be'evident that each of the modifications last described, (Figs. 5*8) as well as in each form of the invention first clescribed, the master gear and work holder are moved to carry that part of the work piece which is adjacent to the cutting point, toward the cutter when receding points in the pitch line of the work approach the cutting position, by the reaction of a cam surface or former in. rigid connection with. the work holder against an abutment, and to carry the same away, when advancing points in said pitch line approach the same position, by the reaction of'the same, or a similar cam or former against a former connectcd with the driving pinion. In the case first described (Figs. 14) the abutment comprises the irregular gear, other than the one to which tl1e,.work piece is secured, and

the floating pinions, thcse'being a floating abutment; while .in the last described caIse the abutment fixed as to its location. both cases the results accomplished arc the the gear in a plane iic l shirt-elects are in all positive in their action, hoe have rolling contact W} ii iflhe reoclin'g sorfaces, Whereb xbhe desired reenit is acre:

1 accuracy an o plished with. the the minimum of The foregoing ings rel'iting the of cnnmng goalie, tic

rel reeisezince.

.ption onci '5 1e drewnstrelze the two is, the ini' ncl and the external of any form or character of irregular- 3 may he cni; the means herein. (iescribecl, since Whoi er bheic form may be, the Work carried out wili have irregnhrrities conforming exactly 50 those ofthe master gear.

The term irregular used in this specilication and in ice foilowing claims, hos special meaning applied to meaning any form of gear whereof the line of teeth is otherwise than concentric with the axis about which. either the gear is designed to rotate, or a. pinion. in mesh with the gel. is designed. to revolve when traveling around 3/ manner.

Although have ho'wn and iicsriheti the part 18, and correspondingly l a coil 38, as a Work holder, wish to pmni; out that I do not limit the. invention to an e 'vpzirein in which there is e \sfilh. holder so- 'LiiL additional to the master gear.

1 eiiece the holder is simply o convenient means for connecting the hizinl: or work piece to the master chceen the iciiel. m Which the Work is to conform, and 10 all intents and purposes Lhe Worh holder is av port of such rooster geznx it mescorrectly consi lerecl therefore that fl master gear is the Work holc ler itself, and the part 18 is the means which indirectiy coni'iccts the Work to such master gear. The term Work holder may he considereci cs embracing the master gear and '50 include arran-geinmit in. which the, WOl'ii piece it; clirec'sly mounted. on. such nice er Without the ifllifil'lfiflr tion of en; nitermedioie holder, ,Well me the eineice here shown in ii h 1h such. intermediate hoiclcr is ei'nployei,

Nhai'i claim and. to secure ere 1. machine for g irreguhir gears comp is' bien -ll0l 1f, a cutter having l'he projections, means for prosiucing rei win movement-e between me cutter the hie r, means for shifting; i

by Leshleni ncicler,

ising h ring sinion liM ifll' e former similar to pitch. iine, on 'megrei oi. an external. hoih meshing Wi'rfih l pinion. end. each. hevi a, former so? iiace {runner the pitch hne of 1138 meeiih liflfl lli'; contact with the former of the pinion, poini', of pitch line ten g cncy helzw n the d. iving; pinien and me of Hfl lacing :linemeni; ii. the iii. piizeh. "no can hl ii, one counseled. to izhc "r-iirions .i?l1.b8lrnei'l 1 having to "he former of goers and in COI'HlOiILiZlOL'l Wilbh a robotic, end E' ily movable shaped cn'lrlzer, work c. "inn soineiie in cpproximece axial. ahnernenf said cutter, e master pinion. on s; id spindle cr ongecifiwith o poini, in iis pitch. iine in o line parallel With its axis gassing rough e.- ooiririn he pitch line of cutter, and l! egnlar master in esh with said pinion, "the Work piece being rigidly connected with one of em mesl er :3, machine for generating and cuizn niegular gears, e means i 01."

moving Work piece, compris mg; :1 master gear to VlllCil the Work piece is rigidly connecteci, :1 driving pinion in mesh nch soul and a second i ster gear :1. 1th the drivin I) i, one oi: seicl. i118 more being an iternei other H161 gczu rii..li'1'}ll3l(llh i. find. the ir' i i T i roiling n iz'iGglllitl gears, a means and izioi ing :3, wo:l-: piece, P/mnpliil gear to which the Work connected, driving pinion in with said. gear, second roaster gee-r i 'th l1 c driving pinion, one oi. our]. in: er gears being snrrcuml ,hc oeher master gear and. the driving pinion, and o liable on which said. gears are supported. with freedom to more liao'th rots ively and lireiishiiiively.

In a ear co, the coin oily reciprccmfio y I cnlzter, of o supporting ole, a master g 11' having an irrc 'nhir pitch line, with which the Work 1 s conneched, a spindle in up iroziii'ne'lze :iliiiemeni; with lzhe cotter, a. driving pinion Hi h'zilil spin flle in inesl'i with said. gear, we gem. being :e to more upon. the table,

c on oi and pinions in floating;

hi i

mesh will said {lriving pinion, with said zinc. with one another, or igedl pose the olriving inion in pitch-1.

on internal gear movements of lihe master gear .on which said master gear is line tangent rolling contact therewith,

whereby the work piece is given a similar inastergcar within the space surrounded by the internal gear, and a number of pinions siaced. about the external gear between the latter and the internal gear and in mesh with both, a driving spindle connected with one of said pinions, the other pinions and gears resting on said support and being free to move over the surface thereof, and means :t'or nttac'hinga gear blank to one of said master gears.

'Z. In a gear cutting machine having a cutter, a means for supporting and so moving a gear blank as to cause the cutter to produce an irregular line of teeth in such blank, comprising an irregular master gear to which the blank is connected, a support adapted to move, a driving pinion in mesh with said master gear located with the tangent point of its pitch line conta'ct with the gear in toe path of travel of the acting part of the cutter, a second master gear meshing with the driving pinion, and pinions interposed between the teeth of said gears, the said gears and pinions being arranged to cause successive points in the pitch line of the first master gear to pass across such path of travel, whereby the teeth, produced in the blank are cut on a pitch line col'iiorming to that of the master gear.

in a. gear cutting machine having a cutter, a means for supporting and so moving a gear blank as to cause the cutter to produce an irregular line of teeth in such blank, con'iprising an irregular master gear to which the blank is connected, a support on which said master gear is adapted to move, a driving pinion. in mesh with said master gear located with the tangent point of its pitch line contact with the gear in the path of the acting part of the cutter, a secpinion, at the opposite side. thereof from. the point of contact between the pinion and the ond master gear meshing with the driving first master gear, said oc u ')ying the same plane and having approximately the same axis, and a plurality of piuions dis posed in planetary relation to said axis and in mesh. with both gears, whcrcby'to maintain the said tangent point, as the driving pinionvand the first master gear rotate, in said path.

9. A gear blank holding and. driving means for a gear cutting machine compris mg an irregular master gear gear blank is adapted to be driving pinion in mesh with gear, a second master gear 4 said pinion on the opposite to which the connected, a said master a mesh with e the axis lddfastii from the point thereof in mesh with the first master gear, said gears and. pinion being in the same plane, and a number of planetary pinions in. mesh with both gears.

10,11 gear blank holding and driving means for a gear cutting machine comprL- ing an irregular master gear to which the gear blank is adapted; to be connected, driving pinion in mesh with said master gear, a second master ear in mesh with said pinion or the opposite side of the axis from. the point thereof in mesh with the first master gear, said gears and pinion being in the v same plane, and a. number of planetary pinions in mesh with both gears, said gears and pinions all having former portions or surfaces corresponding to the pitch lines of their teeth arranged tangent one to another.

11, A gear blank holding and driving means for a gear cutting machine comprising an irregular master gear to which the gear blank is adapted to be connected, a

driving pinion in mesh: with said master gear, a second master gear in mesh with said pinion on the opposite side of the axis from the point thereof in mesh with "the first mas 'ter gear, said gears and pinion being in the same plane, and a number of planetary pinions in mesh with both gears, each of said pinions and gears having, a smooth former surface similar to the pitch line of its teeth and being tangent to the former surfaces of: the gears and pinions with which it meshes. 2. A. go: r blank holding and driving means for a gear cutting machine compris ing an irregular master gear to which the blank is adapted to be connected, a. driving pinion in mesh with said master gear, a second master gear in mesh with said pinion on the opposite side of the aXis from the point thereof in mesh with the first master gear, said gears and ninion being in the same plane, and a number of planetary pinions in mesh with both gears, each of said pmions and gears having a smooth former surface similar in outline to the pitch line of its teeth and in tangent contact with the former surfaces of the other {rears audpinions with which its teeth are respectively in mesh. I i

13. In a machine for generating and cutting, the teeth of irregular gears. in combination with a cutter having cuttingprojcctions of" which the outlines at their cutting,

pitch line'of the cutter which comes tangent to the pitch line of the gear blank,'and a positive means for shifting the master gear toward the pinion as points in receding portions of the pitch line thereof approach the tangent position, said means being con structed to permit recession of the master gear when points in its pitch line approach such tangent position. i 14. In a machine for cutting irregular gears, a shiftable gear blank holder includ ing a master gear having teeth arranged in gear, a cam element associated with said master gear, and an abutment in rolling contact with said cam elementadapted to exert pressure positively thereon for maintaining the master gear in mesh with the pinion.

16. A Work holding means for a gear cutting machine comprising a master gear having teeth in a pitch line which is irregular corresponding to the irregularities of the gear to be cut, a driving pinion meshing with said gear, an abutment, and a cam or tormcr having an irregular outline associated with said gear and bearing upon said abutment, the abutment being formed and arranged to maintain the gear in mesh with the pinion.

17. A holder for a gear cutting machine adapted to present an irregular gear blank in position for cutting, comprising an irregu lar master gear, a tab e or support .on which said master gear is mounted in position for shifting thereover, a driving pinion meshing with said master gear, a cam or former associated with said gear having an outline corresponding to the pitch line of the gear, and an abutment bearing against said cam, the abutment being so arranged and the cam so designed as to cause and permit the gear to shift over said table as successive points on the pitch line oi? the gear come tangent to the pitch. line of the pinion.

18. In a work holding means for a gear cutting machine, an irregular master gear having a pitch line corresponding to that of the gear to be cut, and adapted to be rigidly connected with a gear blank, a driving pinion meshing with said irregular gear, and positive means for maintaining the pitch line of the gear in constant rolling contact with the pitch line of the pinion.

19. In a gear cutting machine, a means for supporting and giving generating movements to an irregular gear blank, compris ing a master gear having an irregular pitch line with which the gear blank is connected and having an. integral cam or former element of which the outline corresponds to its pitch line, a driving pinion meshing with said and having an integral former or cam portion correspmnling in outline to its pitch line and in tangent contact with said portion of said master gear, and means for maintaining the said formers. in contact with one another. I

. 20. In a gear cutting machine, a means for supporting and giving generating move ments to an irregular gear blank, comprising a master gear having an irregular pitch line with which the gear blank is connected, and a pinion meshing with said master gear, said master gear and pinion carrying cam elements in contact with one another andbeing similar in outline respectively to the pitch line of the gear and the pitch line of the pinion, and being so related to such pitch lines respectively as to limit the interpenetration of the teeth of said gear and pinion to pitch line tangency.

521. In a gear cutting machine, amcans for supporting and giving generating movements to an irregular gear blank, comprising a master gear having an irregular pitch line with which the gear blank is connected, a former associated with said master gear having its periphery similar to the pitch line of the gearbut projected beyond the same at all points, and the driving pinion having an associated former of which the periphery is similar in outline to the pitch line of the pinion but retracted at all points within such pitch line a distance equal to the projection of the first named former beyond the pitch line of the master gear.

In testimony whereof I have aihxed my signature.

EDWIN n. rnttows 

